Kim Kardashian and Kanye West have poured boatloads of cash into their Hidden Hills home over the past few years, but it was all worth it ... because the house is now $20 million ABOVE water.

Sources tell us ... the couple sunk around $20 mil into renovations since they bought the property -- once owned by Lisa Marie Presley -- in 2014 for $20 mil. It's been in a constant state of design, re-design, construction and expansion -- not to mention all the landscaping -- until they finally moved in a few weeks ago.

Now get this ... we're told Kim and Kanye had the property appraised ... and the estimated value is $60 million. Do the math, and they're in the black $20 mil.

As we reported ... the couple's new compound includes a full music lab for Kanye, a huge master bedroom addition, a spa and massive closet space. We're told there's plenty more to come in backyard magic.